1. Field of the Invention
The present invention relates to a stag unit having a means for limiting the moving range of a moving table on which a target positioning object is mounted, a drive table driven by a linear motor and capable of easily performing origin detection, and a scanning exposure apparatus for manufacturing semiconductor elements or the like by using the same.
2. Related Background Art
To manufacture semiconductor elements, liquid crystal display elements, or the like by using the photolithography technique, a projection exposure apparatus is conventionally used, in which a pattern formed on a reticle (or a photomask) is exposed, through a projection optical system, onto a wafer (or a glass plate) coated with a photoresist.
In recent years, one chip pattern of a semiconductor element or the like tends to become larger. For this reason, a projection exposure apparatus for exposing a pattern on a reticle, which has a larger size, onto a wafer is required. To meet such a requirement for increasing the exposure area with a so-called step and repeat type projection exposure apparatus for performing full exposure of the entire pattern on the reticle, the projection optical system must be made larger. However, this results in an increase in manufacturing cost of a projection optical system having high imaging performance on the entire surface of the wide exposure field.
Therefore, a so-called step and scan type scanning exposure apparatus has received a great deal of attention. In this apparatus, after each shot area of the wafer is moved to the scan start position, the reticle, which is being illuminated, is scanned in a direction crossing the optical axis of the projection optical system. In synchronism with this scanning, the wafer is scanned in the direction crossing the optical axis of the projection optical system, thereby exposing the pattern of the reticle onto each shot area of the wafer.